Means for securing blades in turbines.



P. KNIGHT. v EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE S.

V IIIIIIIIIIIIIIIII no. 222222 0. I 1 059 618 Patented Apr. 22, 1913.

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PERCY KNIGHT, 0F ANGLESEA, ENGLAND.

MEANS FOR SECURING BLADES IN TURBINES.

Specification of Letters Patent.

Application filed December 22, 1910.

Patented Apr. 22, 1913.

Serial No. 598,805.

To all whom, it may concern Be it known that I, PERoY KNIGHT, of 4.-iVesley Terrace, I-Iolyhead, Anglesea, England, Great Britain, engineer,have invented new and useful Improvements in Means for Securing Bladesin Turbines; and I do hereby declare that the following is a full,clear, and exact description of the same, reference being had to theaccompanying drawings, forming a part hereof.

This invention relates to improvements in the method of securing theblades in the rotor or casing of a turbine whereby a con- 'siderableeconomy in the fixing of the blades may be achieved and the blades bemore effectually secured in the grooves, of the rotor or casing againstany liability of their becoming displaced by reason of centrifugalaction or expansion or creep due to variations of temperature.

With this end in view my invention consists in providing the roots ofthe blades with means adapted to be engaged by a memher located in thegrooves in the rotor or stator casing in such a manner as to preventthem being accidentally displaced when once assembled in position.

In order that my said invention maybe readily understood and carriedinto practice by those skilled in the art to which it appertains I willnow proceed to describe the same fully for which purpose reference is tobe had to the accompanying drawings in which Figure l is a view of ablade under this invention. Fig. 2 is a view of a portion of a row ofblades showing the position they occupy when first arranged in thegroove of the rotor or stator casing and Fig. 3 is a similar view butshowing the blades permanently secured in position. Fig. 4 illustrates aslightly modified form of my invention.

Accordin to this invention the blades a are made 0 continuous sectionsuch as from cold drawn or extruded bars as now gen- .erally adopted andare notched as at b on their edges 0 near the roots d of the blades.These notches are formed at such a distance from the lower extremity ofthe blade that they lie below the outer surface e of the rotor or statorcasing when the blades are inserted in the grooves f. The blades abefore being inserted in the grooves are assembled in sets, the notchesb in the blade roots (1 of each set being engaged by an angle portion orflange 9 which may be termed the axial fiangeof a short curved sectionof angle bar it the other or radial flange of the bar lying against theedges of the blades below the notches. The axial width of the slots orgrooves in the casing or rotor is just suificient to permit of theinsertion of a section of the blades with its curved angle bar.

Before being inserted in the grooves f each section consisting of aseries of blades a with their curved angle bar it and pitch or distancepieces disposed between the roots of the blades may all be brazedtogether at the roots so as to form an integral blade section but ifrequired the set of blades in position on the angle bar may be insertedin the grooves the pitch pieces being afterward set between the bladeroots. In each form whether brazed to the blades, or left free. theposition of the angle bars h, when the blade roots bottom in thegrooves, is such that a slight clearance z is left between the innercircumferential edges of the radial flanges and the bottom of the grooveand the outermost edge of the groove is slightly above the corner of thecurved angle bars. The metal of the casing or rotor at this edge is thenWorked over on to the corner of the angle bars as shown at y Fig. 3forcing the angle bar down in the groove and consequently also each ofthe blades. The angle portion 9 of the curved bars may be less than aright angle, and with respect to the body it, the notches may be formedto correspond and in this way any tendency of the blades to work outradially from the grooves, acts to open the angle bar thereby wedgingthe blades firmly against the opposite wall of the groove. If desirednotches and retaining angle bar sections may be provided at both sidesof the blades as for instance as shown in Fig. 4.

The retaining angle bars are made of suit able metal to provide againstany possibility of their working loose in the grooves after being fixedtherein owing to the expansion or contraction of the turbine parts whenunder steam. In the case of the shorter blades the usual shroud ring atthe outer peripheries of the blades may be dispensed with by reason ofthe very efiicient attachment at the roots of the blades.

Such a system may be supplied to the fixbars and pitch pieces may be cutoff as required from cold drawn or extruded bar sections the systemlends itself to extreme economy in fixing while thesecurity of thefastening is absolutely reliable.

What I do claim as my invention and desire to receive by Letters Patentis 1. In a turbine, the combination with a grooved turbine member, andsections composed of assembled blades and blocks with a retaining memberall brazed together to, form an assemblage, one wall of the groove ofsaid turbine member being worked over in overlapping relation with theretaining member to anchor the assemblage to said turbine member.

2. In a turbine, the combination with a grooved turbine member, of aplurality of blades disposed in said groove and having downwardlydirected notches in the sides thereof, and a retaining member anchoredin said groove and having a downwardly projecting flange engaging saidnotches.

In a turbine, the combination with a grooved turbine member, of aplurality of blades disposed in said groove, and a member for retainingthe blades in said groove, one Wall of said groove being worked oversaid retaining member in overlapping relation therewith for a continuousdistance along the periphery of said turbine member to anchor saidretaining member in said groove.

4. In a turbine, the combination with a turbine member provided with agroove having parallel side walls and a bottom Wall, blades and spacingblocks having parallel side portions engaging the bottom and one of theside walls of said groove and being free from engagement with theremaining side wall of the groove, said blocks and blades having notcheson their free side por tions, and an angle strip provided with an angleportion engaging said notches and a body portion having fiat parallelwalls engaging the free wall of said groove and the free sides of saidblock and blades, the

height of the body port-ion being less than the depth of the groove andsaid notches being located to maintain the bottom of said body free fromthe bottom of said groove and the top of said body below the outer faceof said member, the margins of said turbine member being worked over theouter face of said strip, substantially as described.

5. In a turbine, the combination with a turbine member provided with agroove hav ing parallel side walls and a bot-tom wall, blades andspacing blocks having parallel side'portions engaging the bottom and oneof the side walls of said groove and being free from engagement with theremaining side wall of said groove, said blocks and blades havingnotches on their free side portions, and an angle strip provided with anangle portion engaging the notches in said blades and blocks and havinga body portion reduced in height with respect to the depth of saidgroove, the notches of said blades and grooves being located to maintainthe bottom of said body portion free from the bottom of said groove,substantially as described.

6. In a turbine, the combination with a turbine member having av groovetherein, blades and blocks disposed in said groove and having notches onone side thereof, and an anchoring strip having an angle portionengaging said notches and a body portion disposed between one wall ofthe groove and the blades and blocks, the lower extremity of the stripbeing free from engagement with the bottom of the groove and the upperextremity of the strip being below the face of the turbine member, saidturbine member being worked over said strip to anchor. the same and saidblades and blocks, substantially as described.

In testimony whereof I afiix my signature in presence of two witnesses.

' PERCY KNIGHT. Witnesses:

G. B. STEPHENSON, J NO. H. I-IEBLETHWAIT Copies of this patent may beobtained for five cents each, by addressing the Ger'nmissi'oner ofratents, Washington. I). G.

